Mini blinds have been known and used for many years for the selective admission of light into a room and for privacy. Typically, mini blinds are installed at a window opening and include a plurality of slats that can be pivoted between an open horizontal position and a closed nearly vertical position.
A conventional mini blind includes a head rail mounted to head rail supports positioned near the top of the window opening. The head rail generally has a U-shaped cross-section with an open interior for receiving the various components that control the pivotable slats. The head rail also includes a number of apertures for access to the various control components, e.g. flexible ladders, basket assemblies, and drawcord assemblies.
The flexible ladders which support the pivotable slats are usually connected to the basket assemblies through appropriate apertures in the bottom of the head rail. Additionally, access holes are provided for the pullcord which raises and lowers the bottom rail and the slats, and for the rotating wand used to control the tilter bar which with the basket assemblies. The basket assemblies, in turn, facilitate control of the flexible ladders which allow the slats to pivot between the open and closed positions.
The basket assemblies generally include a framework which rests within the open interior of the head rail and a rotator element to which the flexible ladders are attached. The ladders each have two flexible strings which are suspended from this rotating element with the strings being connected over opposed sides of the rotating element. Thus, when the rotator element is rotated in one direction., one string will be lowered while the other string is raised, and the opposite result is achieved when the element is rotated in the opposite direction. Each ladder also includes a plurality of cross links connected between the two strings. The slats are positioned over these cross links along the length of the ladders. When the rotator elements are rotated, the slats are pivoted as one end of each cross link is pulled upwards while the other end of each cross link is lowered.
To ensure that each ladder and its respective cross links are pivoted the same amount, a tilter bar extends through each rotator element. The tilter bar is connected to a gearbox at one end of the head rail which, in turn, is connected through an appropriate aperture in the head rail to the rotating wand. Thus, a person may rotate the tilter bar by rotating the wand and pivot the slats to a position that allows total privacy or the desired amount of light to pass through the mini blind.
Usually, a pullcord is also employed with a mini blind so the user may raise or lower the slats in the window opening. Generally, the pullcord enters the head rail through an opening equipped with a locking mechanism, extends along the interior of the head rail, and includes a cord that passes out of the head rail at each socket. Each cord passes through axially aligned apertures in the slats and is connected to a bottom rail below the slats. By pulling on the pullcord, the bottom rail will be raised, thereby raising the slats. The locking mechanism is positioned in the pullcord aperture so the pullcord may be locked and the bottom rail suspended at any point between a fully raised position and a fully lowered position.
In current mini blind systems, problems exist with both the head rail and the baskets. Current head rails have a flat bottom wall. The open design does not resist bending, especially when the head rail extends over a long span. Additionally, during manufacture of a mini blind with this type of head rail, it is difficult to determine when the baskets are accurately located over the cord and ladder apertures. Consequently, the basket installer must often make time consuming adjustments to basket position after the baskets are initially installed into the open portion of the head rail. Also, the flat bottom wall can interfere with the pivotal movement of the uppermost slat towards a fully closed position (i.e., vertical). For instance, the top edge of the uppermost slat may contact the bottom wall of the head rail restricting further pivotal motion of the slats and leaving small spaces between the lower slats through which excess light may filter. It would be advantageous to have a head rail designed to alleviate these problems.
Additionally, full closure of the slats is also inhibited by the design of the ladder apertures and cord apertures in both the bottom wall of the head rail and the basket assemblies. Typically, the lower wall of the head rail includes three openings beneath each basket assembly. Ladder strings are threaded through the outermost apertures, while the drawcord extends through the center aperture. The basket has matching apertures which are aligned with the three head rail apertures when the basket is installed. Since the support strings of the ladder go through apertures separated by a central drawcord aperture, the strings cannot move close enough to one another in the fully closed position to fully pivot the cross links and pivotable slats to a vertical position. It would be advantageous to design both the basket and the head rail so the ladder strings could move sufficiently close to one another that full closure is accomplished.